What does FISH testing stand for in breast cancer?
FISH stands for fluorescence in situ hybridization. It's a laboratory test used to measure the amount of HER2 genes inside breast cancer cells.
This test helps determine if your breast cancer is HER2-positive or HER2-negative, which is important for choosing the right Show Full Answer
What does FISH testing stand for in breast cancer?
FISH stands for fluorescence in situ hybridization. It's a laboratory test used to measure the amount of HER2 genes inside breast cancer cells.
This test helps determine if your breast cancer is HER2-positive or HER2-negative, which is important for choosing the right treatment. FISH uses special dye that binds to the HER2 gene so it can be counted under a microscope.
You might need FISH testing if your initial HER2 test results are unclear (scored as 2+). The test can usually be done using cells from your original biopsy sample, so you typically won't need another procedure.
Results are reported as either FISH-positive (meaning HER2-positive cancer) or FISH-negative (meaning HER2-negative cancer). They're usually available within a few days.
November 23, 2025
Join
Your Privacy Choices
